You don't need to have an account with the broker to use the app, you can create a Demo account from the app itself.

To create a Demo Account, go to the Login screen or to the Help section and look for the "Create Demo Account" option. Once created, log in with your Demo Account, you will be able to simulate trading with full iBroker functionality. All trading taking place in this account is Demo, so no real money is made or lost.

If you'd like to open a Live account, you may fill out the "live account" form you may find the live login screen. Fill in the form and a broker representative will get in touch.